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AQA AS Biology > 3.1 BIOLOGICAL MOLECULES - Structure of DNA and RNA, DNA replication, ATP. Water, Inorganic Ions > Flashcards

3.1 BIOLOGICAL MOLECULES - Structure of DNA and RNA, DNA replication, ATP. Water, Inorganic Ions Flashcards

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1
Q

What is the role of DNA?

A
  • In all living cells
  • Holds genetic information
  • important for information carrying cells
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2
Q

What is RNA?

A
  • in all living cells

- transfers genetic information from DNA to the ribosomes.

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3
Q

What is a nucleotide?

A
  • consists of a pentose, a nitrogen-containing organic base and a phosphate group.
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4
Q

What bond is found between two nucleotides?

A

A phosphodiester bond.

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5
Q

What bases can DNA have?

A
  • Adenine-Thymine

- Cytosine-Guanine

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6
Q

DNA has a ______ pentose

A

Deoxyribose

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7
Q

RNA has a ______ pentose

A

Ribose

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8
Q

What bases does RNA have?

A
  • Adenine, Cytosine, Guanine, Uracil.
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9
Q

What is the structure of DNA?

A
  • a double helix with two polynucleotide chains held together by hydrogen bonds between base pairs
  • Fairly long structure of about 2m.
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10
Q

How many H bonds does C-G have?

A

3.

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11
Q

How many H bonds does A-T have?

A

2.

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12
Q

What is the structure of RNA?

A
  • a single polynucleotide chain
  • relatively short.
  • no hydrogen bonds between base pairs.
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13
Q

How is the DNA structure related to its function? (6)

A
  • Hydrogen bonds (weak) can allow DNA to separate during DNA replication and protein synthesis.
  • Large molecule so carries an immense amount of genetic information.
  • Double helix and coiled so compact (a lot of it can fit in a small space)
  • Base sequences allow information be be stored and codes for amino acids.
  • Base pairs protected by phosphate backbone to protect it from being corrupted by outside chemical reactions.
  • Stable structure which passes from generation to generation so rarely mutates.
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14
Q

How do the organic bases stabilise the structure of DNA?

A

There are many hydrogen bonds between the base pairs which provides strength.

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15
Q

What is semi-conservative replication?

A

Where DNA makes exact copies of itself to ensure genetic continuity between generations of cells.

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16
Q

What does the process of semi-conservative replication involve?

A
  1. DNA helix unwinds and the DNA helicase breaks the hydrogen bonds between the complementary base pairs.
  2. Two strands of DNA are separated.
  3. New DNA nucleotides bind to exposed bases on the DNA template strand.
  4. DNA polymerase catalyses the condensation reaction that join adjacent nucleotides.
  5. All nucleotides are joined to complete polynucleotide chain where one half of the chain is new and one half is old.
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17
Q

What is DNA helicase?

A

an enzyme responsible for the unwinding of the DNA molecules by breaking the hydrogen bonds between the base pairs.

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18
Q

What is DNA polymerase?

A

an enzyme responsible for forming covalent bonds between the DNA nucleotides to form a DNA polymer.

19
Q

What is ATP?

A

a nucleotide derivative consisting of ribose, adenine and three phosphate groups.

20
Q

What happens when ATP is hydrolysed?

A

Energy is realises to form ADP and an inorganic phosphate molecule (Pi)

21
Q

What is ADP?

A

consists of ribose, adenine, and 2 phosphate groups.

22
Q

What is ATP hydrolase?

A

an enzyme that hydrolyses/break down ATP.

23
Q

Where does the energy come from?

A

The bonds between the phosphate molecules.

24
Q

Describe the bonds between the phosphate molecules:

A
  • very unstable
  • so have a low activation energy
  • so breakdown is quick and released a lot of energy
25
Q

What happens when ATP undergoes a condensation reaction?

Give two examples.

A
  • ADP synthase catalysed ADP and Pi to produce ATP during photosynthesis and respiration.
26
Q

Why is ATP is very good source of energy? (5)

A
  • stores and releases small amounts of energy at a time so energy isn’t wasted and can be easily reformed
  • small and soluble so can be transported easily around the cell
  • low activation energy so can release stored energy quickly
  • Immediate supply of energy because it cannot pass in and out of a cell
  • ATP can be broken down in a single reaction
27
Q

What happens when Pi is used to phosphorylate other compounds?

A

Makes them more reactive.

28
Q

Role of ATP in metabolic processes?

A

energy to build macro molecules from their basic units

29
Q

Role of ATP in movement?

A

Energy provided for muscle contraction

30
Q

Role of ATP in active transport?

A

provides energy to change the shape of carrier proteins so molecules can move against the concentration gradient.

31
Q

Role of ATP in secretion?

A

forms lysosomes for secretion of cell products.

32
Q

Role of ATP in activation of molecules?

A

Pi is released during ATP hydrolysis which can be added to other substances to make them more reactive.

33
Q

Water being a metabolite:

A

in many metabolic reactions including condensation and hydrolysis

34
Q

Water is an important solvent:

A
  • metabolic reactions occur. The positive ends of the water molecule are attracted to the negative ends of the water molecule so ion will due to its polarity.
35
Q

Water being relatively high in heat capacity

A
  • buffer (resist) changes in temperatures as H bonds can absorb a lot of energy.
  • Does not experience rapid temperature changes so gives good habitat and maintains constant body temperature.
36
Q

Water has a relatively large latent heat of vaporisation

A
  • Takes a lot of energy to break the bonds between H2O molecules.
  • providing a cooling effect with little loss of water through evaporation e.g humans.
37
Q

Water has strong cohesion

A
  • between H2O molecules support columns of water in the tube-like transport cells of plants and produced surface tension where water meets air.
  • Allows water to flow together and aids transport
  • Water to travel up the xylem cell
38
Q

What are the 5 properties of water?

A 
Metabolite
High heat capacity
strong cohesion
Solvent
Large latent heat of vaporisation
39
Q

What are inorganic ions?

A

Ions that occur in solution in the cytoplasm and body fluids of organisms and do not contain a carbon atoms.

40
Q

What are the 4 main ions?

A

Hydrogen, iron, sodium and phosphate

41
Q

Why are hydrogen ions important?

A
  • Determine the pH

- Higher hydrogen ions mean lower pH so more acidic environment

42
Q

Why are iron ions important?

A
  • Haemoglobin is a protein that carried oxygen around in the blood
  • Has 4 different polypeptide chains each with Fe2+ in the centre
  • This binds to the oxygen.
43
Q

Why are sodium ions important?

A
  • Helps transport glucose and amino acids across membranes

- through the process of co-transport

44
Q

Why are phosphate ions important?

A
  • When this ion attaches to another molecule, it is known as a phosphate group.
  • DNA, RNA and ATP have this group
  • Bonds between phosphate groups store energy in ATP.
  • Phosphate groups in DNA and RNA allow nucleotides to form polynucleotides.

AQA AS Biology (4 decks)

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